Having read through the earlier posts, I see here is resistance in some quarters to the word "Choir". Something of the same feeling here, where we tend to talk about Community Song or Singing Groups. There is a feeling, rightly or wrongly, that you have to be really good and probably audition to get into a choir, whereas most of the singing groups are about enjoying singing together, regardless of how "good" you might or might not be.
There is also a bit of confusion between UK and English here! (Big smiley if Mudcat would let me!)
Up here in Scotland, most groups would have a majority of Scots songs in their reperoire, although there may also be English, Irish, American and others.
One of my friends has set up a website for Scottish Commuity Song Groups detailing all groups that he knows about: others can be added if they so wish. It goes by geographical areas:
See:
http://www.angelfire.com/planet/scottishsonggroups/

Simon Thoumire of Scottish Culture Online and Hands Up for Trad (he organises the Scottish Trad Music awards - a real visionary!) has more recently started a "Scotland Sings" campaign to get more people out there singing. There is a free songbook for download.
See: http://projects.scottishcultureonline.com/scotlandsings/